Glass grinding apparatus



All@ 22, 1944 G. R. RoEscH E-rAL 2,356,433

GLASS GRINDING APPARATUS Filed Aug. 12, 1941 2 Sheets-Sheet l Gttomeg Aug. 22, 1944. G. R. Rol-:SCH l-:T AL

GLASS GRINDING APPARATUS Filed Aug. l2. 1941 2 Sheets-Sheet 2 Patented Aug. 22, 1944 GeorgeR. Roesch and Gerald WhiteJ Toledo, Ohio,

assignors to Libbey-Owens-Ford Glass Company, Toledo, Ohio. a corporation .of Ohio Application August 12, 1941, Serial No. 406,486

3 Claims. (Cl.Y 51-122) 'I'he present invention relates broadly to grinding apparatus and more particularly to a machine for grinding the edges of fiat sheets or plates of glass and the like.

Although the machine of this invention is not limited to any specific use, it has been designed primarily for and is of especial utility in the edging of so-called glass mirror plates which are used in the making of rear view mirrors'for automotive vehicles and the like. More particularly,` the machine is adapted for grinding the edges of prismatic mirror plates substantially triangular in cross section having the rear surface thereof plane and perpendicular with respect to the upper and lower edges of the plate andthe front surface arranged at a slight angle with respect to the plane surface.

a suitable reflecting medium such as a coating of silver. It has been found that such a mirror makes a very satisfactory rear view mirror for i Fig. 4' isja transverse sectional view showing the .mannerin which a plurality of the glass plates areassociated with one another for grind- 'I'he plane rear surface of the glass plate is provided with automotive vehicles and the like in that it greatly reduces, if not entirely eliminates, objectionable glare from the headlights of automobiles approaching in the rear.-

An important object of the invention is the provision vof an improved machine for grinding the upper and lower edges of one or a plurality of glass mirror plates of the above character rapidly, accurately, and economically.

Another.important object of the invention is the provision of an edge grinding machine of the above character embodying means for supporting and rmly securing a plurality of glass mirror plates in position to be operated upon and for preventing displacement thereof or movement relative to one another during grinding.

A further important object of the invention is the provision of an edge grinding machine of the above character embodying means for indieating the amount of glass to be ground from the edges of the mirror plates and for also indi-- cating when said plates have been ground to the desired predetermined size.

Other objects and advantages of the invention will become more apparent during the course of the following description when taken in connection with the accompanying drawings.

In the drawings wherein like numerals are employed to designate like parts throughout the same:.

Fig. 1 is a plan view of an edge grinding machine constructed in accordance with the invention;

Fig. 2 is a vertical transverse section therethrough taken substantially on line 2-2 of Fig. 1;

Fig. 3 is a detail transverse section through a portion of the glass plate supporting means taken substantially on line3-3 of Fig. 1;

Fig. 5 is a transverse section through a -prisshown in Fig. 5 a prismatic rear view mirror for automotive vehicles and the like comprising a glass plate lli in the form of atriangular prismoid having a plane back surface II extending perpendicular with respect to the upper and lower Y longitudinal edges I2 and I8 thereof anda front surface Il which is arranged at a slight angle with respect to the back surface' II. The back surfacel I is provided withanysuitable type of reecting media, such as a silver coat I5,'covered by a protective backing I8 if desired.

In Figs. 1, 2 and 8 is illustrated a preferred form of machine for grinding 'the upper and lower longitudinal edges I2 and I3 of the triangular mirror plate I0 to render them perpendicular with respect to the back surface Il and also to provide a mirror of desired predetermined width. The machine comprises a reciprocating table I1 provided with wheels I8 which are supported upon and adapted to run along rails I9 andv20. The reciprocating movement of the table IIl along rails I9 and 20 is effected by a rack and pinion drive including a horizontal transverse shaft 2| mounted at its opposite ends in bearings 22 and having keyed thereto pinions 23 and 24 meshing with"'ack bars 25 and 426 respectively secured to the underside of the table. Carried at the forward end of shaft 2| is a hand wheel 21 by means of which the operator can turn said shaft 4to eiect movement of the table I'I iirst in one `direction and then the other along rails I9 and 20. ,l

Supported upon the top of table I'l and positioned along the forward edge thereof is a substantially rectangular supporting member 28 including a horizontal top plate 29 having -a depending skirt 30 around the perimeter thereof. The supporting member 28 maybe secured to the table in any suitable manner such as by means of bolts or the like 8l passing through horizontal base anges 32 formed integral with the depending skirt 30 alongthe back and at the opposite ends of the supporting member 28. A plurality of glass mirror plates III to be edged are adapted to be supported upon the top plate 29 of supporting member 28 along the forward edge thereof and, as shown in Fig. 2 by way of example, six mirror plates III are laid horizontally one upon the other. These mirror plates are alternately arranged so that the thinner portion of one mirror plate is disposed opposite the thicker portion of the adjacent mirror plate or 2. plates. AIBy arranging the mirror plates in this manner, the. bottom surface of the lowermost mirror plate will be horizontal and the topsurface of the uppermost mirror plate also hori- Y zontal. This will greatly facilitate the support- The stack of mirror plates I9 is secured in place by a sultable number of clamps 94 slidably carried by the supporting member 29 so that they can be moved longitudinally thereof to the desired positions. To this end. the top plate 29 of supporting member 29 is provided intermediate the front and rear longitudinal edges thereof with an undercut channel 99, and each clamp 34 comprises a g'uide block 99 slidable within said channel. Formed integral with the guide block 39 are the spaced, upstanding arms 31 and 99 carrying at their upper ends a horizontal pin 99 upon which is pivotally mounted a substantially horizontal lever 49. Carried at the forward end of lever 49 is a vertical bolt 4I provided at its lower end with a ball-like head 42 received within a socket 49 formed in a circular clamping block 44, said clamping block being preferably covered with rubber, rubber composition or the like 49 which will not mar the glass. Threaded through the rear end of the lever 49 is a vertical bolt 49 to the lower end 41 of which is secured a pad 49 also of rubber, rubber composition or the like. Fixed to the upper end of bolt 49 is a hand wheel 49.

' When it is desired to secure the stack of mirror plates I9 upon the supporting member 29, the clamps 94 are moved along said supporting member to the desired positions. 'Ihe clamping block 44 of each clamp 34 is then moved to engage the uppermost mirror plate and the bolt 49' threaded downwardly through the lever 49l until the pad 49 engages the top plate 29 of supporting member 29. Continued tightening of the bolt 49 will'result in the rear end of lever 49 being moved upwardly along bolt 49 to cause the forward end thereof carrying clamping block 44 to be urged downwardly to firmly clamp the stack of mirror plates in place.

Inorder to'facilitate the proper positioning of the s tack of mirror plates I9 upon the supporting member 29. there are provided two or more stops 99, each comprising a substantially rectangular block carried by a bolt 9 I, said bolt passing downwardly through said block and having threaded upon its lower end a nut 92 received within the longitudinally extending channel 35 in supporting member 29. i The stop block 99 is preferably provided with a covering 53 of rubber, rubber composition, orother suitable cushioning material against which the inner edges of the mirror plates are adapted to abut as -shown inFigs. l and 3. e

Aspclearly illustrated in the drawings, when the stack of mirror plates I9 is secured upon the supporting member 29, the forward edges thereof to be ground project slightly beyond said supporting member and table` I1. The grinding of the forward edges of the glass plates is eifected by means of a grinding wheel 94 rotatable upon a horizontal shaft 99 journaled in a bearing 99 mounted upon a horizontal platform 91. Fixed 76 demanded, and therefore the provision of theV to the grindingv wheel shaft u is s puney n about which is trained a belt 99 also running around a pulley 99 keyed to the shaft 9| of motor 92 also mounted upon horizontal platform'91.

The grinding wheel 94 serves to effect the grinding of the forward edges of the stack of mirror plates I9 as said plates are moved slowly ilrst in one direction an'd then the other past said grinding wheel in contact therewith. The reciprocating movement of the table I1 is accomplished by rotation of the hand wheel 21 by the operator. The horizontal platform 91 is supported upon a horizontal base member 93 for movement toward and away from the table I1. The desired horizontal adjustment of the platform 91 may be eifectedby means of a bolt 94 threaded through a bearing 99 and suitably attached at its forward end to said platform 91, while carried upon the outer end of bolt 94 is a hand wheel 99. By turning the hand wheel 99, the platform 91 can be moved inwardly or outwardly to properly position the grinding wheel 94 with respect to the mirror plates to be operated upon.

After one longitudinal edge of the stack of mirror plates I9 has been ground, the stack of plates is reversed and the other longitudinal edge ground. In practice, it is preferred that approximately one-half of the glass to be removed be ground from one edge of the mirror plate andthe other half ground from the opposite edgeV thereof. In order to indicate the amount of material to be removed and also to indicate when this has been done, suitable indicating means including a micrometer 91 is provided. The micrometer is carried at the upper end of a vertical 'arm 99 secured at its lower end to the upper end 99 of a bracket 19 by means of a bolt or the like 1I passing through a slot 12 in arm 99. The bracket 19 is substantially L- shaped and the horizontal portion thereof secured to the bottom of rail I9 by bolts or the like 13.

'I'he numeral 14 designates a vertical lever pivoted intermediate its ends as at 19 to the bracket 99 and carrying at its lower end avfreely rotatable roller 19 engaging the forward edge of the stack of mirror plates I9. The upper end of lever 14 is engageable by the stem 11 of the micrometer 91, said micrometer having the usual rotatable pointer 19 and graduations 19. The roller 19 is normally maintained in engagement with the stack of mirror plates by means of a tension spring 99 fastened at one end tothe upper end of the lever 14 and at its opposite end to a lug 9| on arm 99. The outward movement of the upper end of lever 14 is limited by a stop bolt 92'threaded through a lug I99 also carried by arm 99.

When the stack of mirror plates I9 is secured upon the supporting member 29, the micrometer 91 will indicate the amount of glass to be ground from the edges of the plates and, as stated above, it is preferred that approximately one-half of the glass be removed from each of the longitudinal edges of the mirror plates. Consequently, when the micrometer indicates that approximately one-half of the glass to be removed has been ground off, the position of the mirror plates is reversed and the opposite edges ground until the micrometer indicates that the total desired amount of glass has been removed. In producing mirror plates of this type for use in forming rear view mirrors., relatively close tolerances are micrometer 81 serves a very important purpose in determiningjust how much glass is to .be re and corners forms the subject-matter of our Patent No. 2,283,289, dated May 19, 1942. After the edges and corners of the mirror plates have been properly ground, the back surface II thereof is provided with a suitable mirrorl coat I which may be covered with a suitable backing I6 if desired. 'I'he protective backing I6 can also extend over the upper and lower edges I2 and I3 of the mirror plate if desired as shown in Fig. 5.

The clamps 34 serve to firmly secure the stack of mirror plates against displacement during grinding as well as preventing any relative movel ment between adjacent plates. These clamps also permit a stack of mirror plates to be easily and quickly secured in place andthe position thereof readily reversed after the grinding of one edge thereof. In arranging the mirror plates as shown in Fig. 2, it is preferred that a sheet of paper 84 be interposed between adjacent plates to minimize the liability of scratching of adja cent glass surfaces and provide a cushion between adjacent plates. clamp 34 passes through openings 85 in the vertical arms 31 and 38, and a plurality of pairs of'openings 35 may be provided to permit vertical adjustment of the horizontal lever 40 depending upon the number of mirror plates being ground. Due to the provision ofthe vertical slot 'I2 in the arm 68, the said arm and associated` parts can also beadjusted vertically depending upon the number of mirror plates being operated upon.

Itis to be understood that the form of the invention herewith shown and described isto be taken as the preferred embodiment of the same, and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

We claim:

1. In apparatus for grinding the edges of plates of glass or the like, a horizontally reciprocating table, a substantially rectangular supporting member secured upon the top of said table and including a horizontal top plate provided intermediate the front and rear edges thereof with a longitudinally extending channel, the portion of said top plate forwardly of said channel adapted to support the plate to be ground horizontally thereupon, clamping means comprising a substantially vertical portion slidably mounted within said channel, a substantially horizontal lever pivotally mounted intermediate its ends on said substantially vertical portionto turn about a horizontal axis, a vertical bolt carried at the forward end of said lever provided at its lower en d with a ball-like head, a clamping block having a socket receiving the ball-like head of said bolt therein and adapted to engage the plate to be ground for securing it in position upon said supporting member, a vertical bolt threaded through the rear end of said lever and a pad secured to the lower end of said last-named bolt and engag- 'Ihe horizontal pin 39 of each ing the top plate of said supporting member rearwardly of said channel, said last-named bolt being adapted upon tightening thereof to rock said lever and urge said clamping block into engagemember secured upon the topof said table and l including a horizontal top plate provided intermediate the front and rear edges thereof with a longitudinally extending channel, the portion of said top plate forwardly of said channel adapted to support the plate to be ground horizontally thereupon, clamping means comprising a substantially vertical portion slidably mounted within said channel, a substantially horizontal lever pivotally mounted on said substantially vertical portion to turn about a horizontal axis, a clamping block adapted to engage the plate to be ground for securing it in position upon said supporting member, means for mounting said clamping block at the forward end of said lever for universal movement relative thereto, and means carried at the rear end of said lever engaging the top plate of said supporting means rearwardly of said channel for urging said clamping block into engagement with the plate to `be ground, and grinding means arranged forwardly of said supporting member and adapted to engage the forward edge of said plate upon reciprocation of said supporting member.

3. In apparatus for grinding the edges of plates 1 in said channel, a substantially horizontal lever pivotally mounted on said substantially vertical portion for ready removal and to turn about a horizontal axis, a clamping block adapted to engage theplate to -be ground for securing it in position upon said supporting member, means for mounting said clamping block at the forward end of said lever for universal movement relative thereon, and means carried at the rear end of said lever engagingthe top plate of said vsupporting means rearwardly of said channel for urging said clamping block into engagement with the plate to be ground, a plurality of stops hav-v ing portions slidably mountedwithin said channel and other portions'against which the inner edge of the plate abuts, and grinding means arranged forwardly of said supporting member andl adapted to engage the forward edge of said plate upon reciprocation of said supporting member.

GEORGE R. RoEscH. GERALD WHITE. 

